Wire bonding is an assembly procedure for semiconductor devices in which wires are attached between, for example, a semiconductor die and packaging leads. In wire bonding, bond wires are attached to bond pads located along the periphery of the semiconductor die. Each wire, or wire bond, establishes an electrical connection between a respective bond pad on the semiconductor die and a respective finger or pin of a package lead. The procedure for each bond wire begins with bonding the wire to the bond pad. The bond wire is then extended to position the other end of the bond wire at the lead finger. Once in position, the bond wire is then bonded to the lead finger. The bond wire is then severed, and the process is repeated for the next wire bond connection.
Ball bonding is one type of wire bonding technique for establishing the connections between the wires and the bond pads and the package leads. Ball bonding involves the application of heat to form the weld or connection. In thermo-compression bonding, bonding wire is fed out of a capillary device. A spark or other heat source melts the end of the wire into a ball, which is positioned over the bond pad. The capillary device pushes the molten ball downward onto the bond pad. A bond is formed as a result of the heat and the compression. Once the bond is formed, more wire is fed out of the capillary device to extend the wire to the lead finger. A molten ball may again be formed and pressed against the lead finger to bond the wire thereto. Another spark or heat source severs the wire and forms the ball for the next bond.
Thermo-sonic bonding is another ball bonding technique in which ultrasonic energy is also used to form the ball and establish the bond. The ultrasonic energy is provided by the capillary device through the bond wire.
Ultrasonic, or wedge, bonding is yet another wire bonding technique. Pressure and ultrasonic forces are applied to the wire to form bonds with the bond pad and the package lead. The wire is then severed through clamping and movement of the bonding machine. Wedge-like bonds known as stitch bonds are also formed at intermediate locations at the die or package in some thermo-compression ball bonding procedures in preparation for forming the next ball.
Wire bonding has been used to form jumper connections. The bond wire extends between two points on the semiconductor device to establish an electrical connection. However, such bond wire jumpers may consume excessive space on the semiconductor die. Space for two bond pads as well as at least the minimum distance involved to allow a wire bonder to create the wire jumper. The bond wire jumper may also present excessive inductance, which may limit device performance.